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Maurice D. Awouafack Roland T. Tchuenguem Takuya Ito Jean P. Dzoyem Pierre Tane Hiroyuki Morita 《Helvetica chimica acta》2016,99(4):321-324
The phytochemical investigation of the MeOH extract from fruits of Kotschya strigosa using repeated normal and reversed‐phase column chromatography and Sephadex LH‐20 chromatography led to the isolation and characterization of a new isoflavanol, named kotstrigoisoflavanol ( 1 ), together with three known compounds, diosmetin ( 2 ), β‐sitosterol ( 3 ), and the 3‐O‐β‐d‐glucopyranoside of β‐sitosterol ( 4 ). The antioxidant activity of crude extract, 1, and 2 was determined using the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH˙) method. The crude extract (IC50 61.7 ± 0.2 μg/ml) and 2 (IC50 70.2 ± 0.1 μg/ml) showed moderate antioxidant activities, while 1 was weakly active (IC50 153.1 ± 0.1 μg/ml), as compared with the standard reference l ‐ascorbic acid (IC50 21.9 ± 0.0 μg/ml). 相似文献
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Bosco Peron Leutcha Jean Paul Dzoyem Jean-Bosco Jouda Denis Kehdinga Sema Virginie Flaure Tsague Tankeu Gabin Thierry Mbahbou Bitchagno Billy Toussie Tchegnitegni Flaure Rosette Ehawa Essoung Bruno Ndjakou Lenta Simon Fogue Kouam Florence Delie Alain Meli Lannang Norbert Sewald 《Molecules (Basel, Switzerland)》2022,27(15)
Twenty-two compounds were isolated from the fruit of Albizia lebbeck including one unprecedented, rare amino acid-derived zwitterionic and one new flavone derivative. The isolation was performed on repeated column chromatography over silica gel and their structures were determined by 1D-, 2D-NMR and HR-ESI-MS spectra together with reported data in the literature. The chemophenetic significance is also discussed. Some isolated compounds were reported for the first time to be found in the species. Additionally, compound 2 showed antibacterial activity and compounds 1 and 2 revealed moderate cytotoxic activity against the Raw 264.7 cancer cell line with IC50 values of 37.19 µM and 29.36 µM, respectively. Furthermore, a proposed biosynthetic pathway of compound 1 is described. 相似文献
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Dzoyem JP Kechia FA Kuete V Pieme AC Akak CM Tangmouo JG Lohoue PJ 《Natural product research》2011,25(7):741-749
In?vitro biological activities including phytotoxic, antifungal activities as well as acute toxicity of the methanol extract, fractions and/or isolated compounds from the stem bark of Diospyros canaliculata were investigated. Well agar diffusion and macrodilution assays were used for investigating the antifungal activity. A phytotoxicity assay was performed against Lemna minor while an acute toxicity assay was performed in mice via oral administration. As a result, plumbagin (5-hydroxy-2-methyl-1,4-naphtoquinone) and two known pentacyclic triterpenes (lupeol and lupenone) were isolated from the extract. With regards the antifungal activities, the inhibition zones varied from 16.51 to 24.86 mm and from 20.50 to 25.10 mm for the extract and plumbagin, respectively. The minimum inhibitory concentrations of the extract and plumbagin ranged between 12.5-25 and 0.78-1.56 μg mL(-1), respectively. At 50 μg mL(-1), the hexane fraction showed phytotoxic activities similar to paraquat, the standard phytotoxic inhibitor. The extract was found to be non-toxic to mice after administration per os. Based on the current findings, we can conclude that this extract is non toxic, with significant phytotoxic and antifungal properties due to the presence of plumbagin. 相似文献
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The structural and electronic transport properties of La1−x
Ce
x
MnO3 (x=0.0–1.0) have been studied. All the samples exhibit orthorhombic crystal symmetry and the unit cell volume decreases with
Ce doping. They also make a metal-insulator transition (MIT) and transition temperature increases with increase in Ce concentration
up to 50% doping. The system La0.5Ce0.5MnO3 also exhibits MIT instead of charge-ordered state as observed in the hole doped systems of the same composition. 相似文献
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Rodrigue T. Kengap Gilbert D. W. F. Kapche Jean‐Paul Dzoyem Ingrid K. Simo Pantaleon Ambassa Louis P. Sandjo Berhanu M. Abegaz Bonaventure T. Ngadjui 《Helvetica chimica acta》2011,94(12):2231-2238
A new triterpene, conrauidienol ( 1 ), and a new dihydroflavonol, conrauiflavonol ( 2 ), along with β‐amyrin acetate ( 3 ), betulinic acid ( 4 ), ursolic acid ( 5 ), 6β‐hydroxystigmasta‐4,22‐dien‐3‐one ( 6 ), 8‐prenylapigenin ( 7 ), β‐sitosterol glucoside ( 8 ), and 3,4′,5‐trihydroxy‐6″,6″‐dimethylpyrano[2,3‐g]flavone ( 9 ) were isolated from the stem barks of Ficus conraui Warburg (Moraceae). Their structures were elucidated by spectroscopic analysis. The hexane, AcOEt, and MeOH extracts, as well as the new isolated compounds exhibited selective antimicrobial activities varying from weak to moderate. 相似文献
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Jérôme JP. Leon 《Letters in Mathematical Physics》1981,5(1):75-80
We establish a transformation which connects the potentials of the one-dimensional Dirac and Klein-Gordon operators. This transformation links the solutions of the nonlinear evolution equations solvable by means of the two inverse spectral transforms which use the Dirac and Klein-Gordon direct and inverse spectral problems. 相似文献